Engine-Codes.com
Engine-Codes – Generic – P0504

P0504 Code - Brake Switch Circuit 'A' / 'B' Correlation

Quick Answer

The P0504 code indicates a correlation issue between the brake switch circuit 'A' and 'B'. Common causes include Faulty brake switch, Wiring issues in the brake switch circuit, Corrosion or damage to the brake switch connectors. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0504 indicates Brake Switch Circuit 'A' / 'B' Correlation.
Common causes
Common causes include Faulty brake switch, Wiring issues in the brake switch circuit, Corrosion or damage to the brake switch connectors.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Aug 19, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0504 Description

The P0504 code indicates a correlation issue between the brake switch circuit 'A' and 'B'. This means that the signals from the brake switch are not matching up as they should, which can cause a variety of issues in the vehicle. The brake switch is a crucial component that informs the vehicle's systems when the brakes are being applied, allowing for proper operation of safety features like brake lights, cruise control, and transmission shifting. When there is a correlation problem between the two circuits, it can lead to erratic behavior in these systems and potentially compromise overall safety.

OBDII Code P0504 - Brake Switch Circuit 'A' / 'B' Correlation
P0504 Code - Brake Switch Circuit 'A' / 'B' Correlation

Common Causes of P0504

  1. Faulty brake switch
  2. Wiring issues in the brake switch circuit
  3. Corrosion or damage to the brake switch connectors
  4. Issues with the brake switch circuit control module
  5. Software glitches in the vehicle's electronic control unit (ECU)

Symptoms of P0504

  1. Brake lights not working properly
  2. Cruise control not engaging or disengaging unexpectedly
  3. Transmission shifting irregularly
  4. Inability to shift out of park
  5. Check Engine Light illuminated

How to Fix P0504

  1. Perform a diagnostic scan to confirm the P0504 code and pinpoint the exact cause of the issue.
  2. Inspect the brake switch, wiring, and connectors for any damage or corrosion.
  3. Replace the brake switch if it is found to be faulty.
  4. Repair any damaged wiring or connectors in the brake switch circuit.
  5. Clear the code and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0504

The cost of repairing a P0504 code can vary depending on the specific cause of the issue and the vehicle make and model. On average, the repair cost for this type of issue can range from $100 to $300, including parts and labor. However, it's important to note that labor rates at auto repair shops can vary, so it's recommended to obtain a detailed quote from a trusted mechanic before proceeding with the repair.

What does this mean?

Tech Notes for P0504

Check the Brake Lamp Bulb and Brake Lamp Bulb Fuse first, if the bulb and fuse are OK, then replace Brake Lamp Switch (it is located behind the brake pedal)

Need more information about the P0504 code?

Need more information on how to fix the P0504 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0504 code diagnosed by a professional: Find a repair shop in your area

Code P0504 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0504 Code

No Frequently Asked Questions about P0504 Code found.

Discuss the causes and fixes for P0504 OBDII Code

Submit a New Comment

  • I just got this code on 2004 Toyota Sienna. It burned brake light fuse instantly and when i turn running light also all brake lights went on. It all went down to faulty stop light bulb that caused short circuit.

    Reply to Comment

  • Thanks for sharing!!

    Reply to Comment